1. Field of Invention
The present invention is directed to a process and apparatus for increasing biological activity in ponds and lagoons. More particularly, the present invention relates to a process and apparatus which generates discrete flows in ponds and lagoons resulting in greater biological activity and consequent increase in situ sludge digestion.
2. Background of the Prior Art
Waste treatment ponds and lagoons are commonly employed to pretreat agricultural and industrial waste in a relatively inexpensive manner. Their disadvantages are the large land mass they occupy and their slow speed. It is thus unsurprising that they are commonly sited in rural and other low cost locations. Although the location of the pond or lagoon solves the size problems associated with this waste treatment solution, the speed at which waste is eliminated by this expedient has not been satisfactorily addressed and is the subject of much current activity.
At present the detention time, for sludge and other waste deposited into ponds and lagoons, runs to about 3 weeks. Obviously this term limits the waste throughout and creates local environmental difficulty such as odor and human and farm animal health.
In view of these environmental problems many investigators have advanced processes and apparatus for accelerating biological waste degradation in waste treatment ponds and lagoons. A common expedient in these proposed solutions is the use of aerators for accelerating aerobic microorganism activity. A plurality of aerator designs, provided in U.S. Pat. Nos. 5,564,628; 4,734,235; 3,911,065; 3,797,809; 6,421,221; 6,227,525; 5,980,100; 5,737,562; 5,931,100; 5,510,022; 5,110,510; 4,859,327; 4,734,191; 4,540,528; 4,468,358; 4,350,648; 4,318,871; 4,242,199; 3,958,389; 3,833,173; 3,771,724; 3,739,986; and 3,835,926; and U.S. Patent Application Publication No. 2004/005590, emphasize the large number of such proposed solutions.
These devices, which include circulating aerators, are well known in the art. Of particular interest is an aerator with a floating open-topped dish provided with a solar-powered impeller and a draft tube for circulating sub-surface water along the water surface in substantially horizontal flow with an imbedded draft tube vortex breaker. This device is set forth in U.S. Pat. No. 6,439,853. A similar device, disclosed in U.S. Pat. No. 6,432,302, situates the impeller above the draft tube. In U.S. Patent Application Publication No. 2002/0001529 the upper lip of an open-topped dish is slightly below the water surface. The device taught in U.S. Patent Application Publication No. 2005/0155922 is equipped with horizontal intake with a single circulation zone disposed above the thermocline, the line of demarcation between higher and lower temperature in ponds and lagoons and/or a single circulation zone which eliminates the thermocline. Finally, U.S. Patent Application Publication No. 2003/0127754 teaches a device of the type taught in the '853 patent provided with means for introducing air bubbled in a draft tube, below the impeller, through a diffuser, to increase the oxygen content of the water.
These devices all distribute sub-surface water by freely flowing sub-surface water parallel to but below the water surface. An impeller is used to move sub-surface water to the surface. That is, the prior art emphasizes that wave formation is effectual in a rotating impeller rather than in the chassis to which the impeller is attached.
What these devices share in common is the aeration of the aerobic zone of a waste treatment pond or lagoon. As taught in “Pond Doctor Engineering Brief”, however, a waste treatment pond or lagoon includes facultative and anaerobic zones, as well as an aerobic zone. That disclosure emphasizes that purification occurs faster in the aerobic and facultative zones because bacteria and plants degrade more pollutants in the presence of nutrients, oxygen, heat and light, which are all present in the aerobic and facultative zones.
As such, the absence of agitation of the anaerobic zone explains the limited success of prior art processes and devices for accelerating waste treatment in ponds and lagoons. Thus, there is a strong need in the art for a process and apparatus for mixing oxic and anoxic zones in waste treatment ponds or lagoons which would cause “ . . . useful life forms to flourish in the regions of the pond where their particular diets can be readily satisfied”, as set forth in the Pond Doctor technical article.